Electromagnetic device.



D. D. MILLER.

ELECTROMAGNETIC DEVICE.

APPLICATION FlLED MAR.4| 1915.

Patented Sept. 18, 1917.

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UNITED STATES PATENT OFFICE DANIEL 1). MILLER, on NEW Yocsx, N. r,Asszencm, m2 MESNE sssrenmniws, T WESTERN ELno'rnIc comrnnr,INCQRPQBATED, A CGRPORA'IION or miw roux.

Specification of Letters latent.

latented Sept. 18, 1917.

Application filed March 4, 1915. Serial No. 12,204.

To all whom it may concern:

Be it known that I, DANIEL D. MILLER,

a citizen of the United States, residing at New'York, in the county ofNew York and State of New York, have invented certain new and usefulImprovemc'ntsin Electromagnetic Devices, of which. the following is afull, clear, concise, and exact description. 1 v

The inventionrelates to electromagnetic devices and more particularly toelectromagnetic relays.

The object of this invention is the production of a relay which will beslow both in responding and in releasing.

In accordance with one feature of this invention, the armature of arelay is provicled with an encircling closed circuit coil in which acurrent is induced from current flow in the energizing winding, the flowof current inthe closed coil opposing that in the energizing winding",whereby the pulling up of the structure is delayed when the energizingwinding is brought into circuit with a source of current.

In accordance with another feature of this invention, the armature poleface is convexed so as to concentrate the flux, whereupon, when the flowof current through the energizing winding is interrupted, the convexpole face and the closed circuit coil coiiperate to delay the fallingofl of the armature.

@ther features of this invention relate to combinations of parts anddetails of construction as will hereinafter appear.

This invention is illustrative in the t6- companying drawing, in which-Figure l is aplan view, partly in section, of an electromasnet embodyingthis invention; I

Fig. 2 is an end elevation of the electromagnetic device shown in Fig.1; and

Fig. 3 a. view in perspective of the electromagnetic device shown inFigs. 1 and 2'.

As shown inthe drawing, the electromagnetic device embodying thisinvention comprises an electroinagnet 4, the core of which hits forwardextension 5 forming a pole piece and a; rearward extension 6 forming insecond pole piece. The end of extension 6 may be bifurcated, and thelegs thereof bent at right angles; as shown in- Fig. l, and secured to asuitable meunting strip 7 by means of screws 8, 8. It will be noted thatthe core of the electromagnet it forms a support for the entirestructure of the electromagnetic device. A U-shaped mounting lug 14,suitably secured to the extension 6, supports a U-shaped armature 9hinged to the lug 14. by means of a. flat spring 13 of magneticmaterial. The free end of the armature 9 is provided with a convex pole.face 10 positioned in operative relation to the pole piece 5 of thecore, and with projjectrng lugs 11, 11 which control the movement ofcontact springs 12, 12 mounted upon the extension 6, but insulatedtherefrom and from one another. A screw 15 secured to the end of polepiece 5 passes through an opening provided in the frc'e end of armature9 and is engaged by a locking nut 16. by means of which the distancebetween the pole piece 5 and the conv-ex pole face 10 may be adjusted.The adjustment of the tension of the middle spring 12 or each set issuch that these springs normally hold the free end of the armature 9against the locking nut 16.

@n the armature and linking with the magnetic flux therethrough iscarried an encirclingclosed circuit secondary coil shown in the form ofa plurality oi annular disks 17. 1? conductivelv united. The mag;-netomotive force of the closed secondary coil, due to the induction fromthe How of current through the energizing winding of the eleotromagnetupon connection being established with a. source of current, is opposedto the msgnetomotive force or" the energizing winding and delays thebuilding up of the flux thereby delaying the responding of the armatureto the energizution of the electromagnet.

Now it is well known that upon interrup tion of the how of current in anelectromagnct the magnetomotive force thereof will be reduced topractically zero almost instantaneously, and en armature associated withthe electromagnet will release immedi ately. However, if n.- olosedsecondnry coil is associated with said electromagnet, a mag netomoti've-force will be induced in the closed secondary coil upon theinterruption of the flow of current in the primary coil; This inducedmsgnetomotive force of the closed secondary coil will be in the samedirection as that of the primary coil. This mngneton'iotive some of theclosed secondary coil builds up very rapidly and then decreases veryrapidly for a certain period of time, after which there is a gradualdecrease until this magnetomotive force is dissipated. 5 In the ordinaryelectromagnetic device during this first mentioned period, the densityof the lines of force is suflicient to hold the armature in attractedposition, but during the period of gradual decrease the armature is inits unattracted position. In accordance'with the present invention, thepole face of the armature'is made convex, whereby .the lines of forceare concentrated and for a portion of the period of gradual decrease thedensity of the concentrated lines of force is sufficient to maintain thearmature in attracted position. By the utilization of this invention,the interval of time between the interruption of the flow of curleasingof the armature may be as much as three-quarters (i) of a second. Itwill be readily apparent that a time interval of such magnitude is ofutmost importance where 35 such a device is to be used in associationwith other apparatus in circuits which must be maintained closed forapproximately this length of time, in order that such apparatus may havetime to perform the necessary functions. By employing the presentinvention it will be noted that the armature of an e ectmmagnetic devicemay be rendered both slow responding and slow releasing by meansexternal to the electromagnet proper,

- thereby retaining all the space around the core for the energizingwinding and effecting a large saving in the amount of copper requiredfor the winding. Since the means for rendering the armatureslow-responding and slow-releasingare associated with the armature only,the electromagnet may be used in an ordinary electromagnetic device bymerely changing the armature. Likei5 wise an electromagnetic deviceembodying this invention is readily assembled and may be readilydismantled 'orthe purpose of repairs.

While the closed secondary coil has been herein. described as copperdisks encircling the armature, it is apparent that it may consist of asingle encircling sleeve or bare copper wire wound thereon, and such areto be understood as coming within the scope of this invention.

What is claimed is:

1. In an electromagnetic device, an electromagnet, an armature therefor,and a short circuited secondary coil encircling and linkso ing with theflux in said armature for cooperating with said electromagnet to controlthe movement of said armature.

2.111 an electromagnetic device, an electroniagnet, an armature thereforadapted to 155 move in a direction transverse to the axis of rent in theenergizing winding and the re-- the electromagnet, and a plurality ofcopper disks carried by and linking with the flux in said armature torender it slow-responding and slow-releasing.

8, In an electromagnetic device, a magnetic circuit comprising a coreand an armature, a pole piece for said core, a convex pole piece forsaid armature adapted to have substantially line contact with the polepiece for said core, a primary energizing winding on the core, a closedsecondary coil linking with all the flux in the magnetic circuit, saidclosed secondary coil cooperating with said pole pieces to render thearmature slow-releasing.

4. In an electromagnetic device, an electromagnet, an armature thereforhaving a convex pole face, a pole face on the electromagne't adapted tohave substantially line contact with the convex pole face of thearmature, and a closed secondary coil carried by and linking with theflux in said armature and coiiperating with said contacting pole facesto render said armature slow-releasing.

5. In an electromagnetic device, an electromagnet, an armature thereforhaving a convex pole piece, a pole piece for said electromagnet adaptedto have substantially line contact with the convex pole piece of thearma- 05 ture,'and a closed coil of non-magnetic material carried by andlinking with the flux in said armature for cooperating with saidcontacting pole pieces to render said armature slow-releasing.

6. In an electromagnetic device, an electromagnet, an armature therefor,and a plurality of copper disks carried by and linkin with the flux insaid armature, 00- operating pole pieces for said electromagnet 106 andsaid armature adapted to have substantially line contact with eachother, one of said pole pieces being convex for (206perating with saidcopper disks to render said armature slow-releasing.

7. In an electromagnetic device, an electromagnet having a core withextending pole pieces, an armature mounted on one pole piece and havingthe free end thereof positioned adjacent the other pole piece inoperative relation thereto, a convex pole piece on the free end of saidarmature adapted to have substantially line contact with the opposingpole piece on said core, and a plurality of copper disks carried by anden- 12. circling said armature for cooperating with said opposing polepieces to render said armature slow-releasing.

8. In an electromagnetic device, a magnetic circuit comprising a coreand an ar- 12 mature, opposing pole pieces on said armature andsaid'core adapted to contact over comparatively small area of "theirsurfaces,

a primary energizing winding for the core, a closed secondary coillinking with all the flux in said armature and coiiperating with saidcontacting pei'e pieces to render said armature slow-releasing.

10. In an electromagnetic device an eleccmmeg'i'iet, a ccre and anarmature therefor, opposing pcie pieces for said core and said armatureadapted is have contact over a compeiacively small area thereof, and aclosed secondary ceii carried by and linking with the flux in saidarmature and coiipcrating with said contacting pole pieces to rendersaid armature slow-releasing.

In Witness whereof, I hereunto subscribe my name ibis 2nd day 0f MarchA. D., 1915.

DANIEL D. MILLER, Witnesses:

EDLER,

L. STAHL

